搅拌工艺对多孔类骨料混凝土性能的影响

发布时间：2018-06-05 20:26

本文选题：搅拌工艺 + 珊瑚混凝土　；参考：《广西大学》2017年硕士论文

【摘要】：本文主要研究了改进搅拌工艺(裹砂石法)对珊瑚、陶粒二种不同类型的多孔类骨料混凝土性能的影响,分析了其作用机理,并以石灰石混凝土作参照对比。主要研究内容与结果如下:检测了珊瑚、陶粒、石灰石的吸水率、密度、空隙率、筒压强度、压碎指标、针片状含量等物理性质,并针对多孔类骨料混凝土强度低的特点,确定以裹砂石法作为本文的改进搅拌工艺。通过检测新拌混凝土的稠度、含气量与泌水率,研究了改进搅拌工艺对多孔类骨料混凝土工作性能的影响,并分析了其作用机理。结果表明:改进搅拌工艺能够提升混凝土的流动性,从而减少减水剂的用量;改进搅拌工艺能够降低混凝土的含气量,降幅随着水灰比的降低而增大,其对多孔类骨料混凝土的作用效果强于石灰石混凝土;珊瑚混凝土与陶粒混凝土因骨料密度低而泌水严重,石灰石混凝土无泌水现象,改进搅拌工艺能够改善多孔类骨料混凝土的泌水率,水灰比越低,改善效果越佳。研究了粗骨料性能对混凝土抗压强度的影响以及改进搅拌工艺对多孔类骨料混凝土抗压强度与耐久性的影响。结果表明:三种混凝土抗压强度由高至低依次为:石灰石混凝土陶粒混凝土珊瑚混凝土,与骨料强度排序相符,随着水灰比的降低多孔类骨料混凝土与石灰石混凝土的强度等级差距进一步扩大;改进搅拌工艺能够提升多孔类骨料混凝土的抗压强度,低水灰比时,抗压强度的提升幅度随龄期的变化规律:早期不明显,之后随龄期增长快速增大,进入中后期小幅回落并趋于稳定;高水灰比时,变化规律:增幅明显且较为稳定。在低水灰比时,改进搅拌工艺能够明显提升多孔类骨料混凝土的抗氯离子渗透性能与抗碳化性能,抗氯离子渗透性能的提升幅度随着龄期的增长有所下降,抗碳化性能的提升幅度随着龄期的变化保持稳定,在高水灰比时,无明显提升效果。通过压汞测试(MIP)研究了改进搅拌工艺对多孔类骨料混凝土孔结构的影响,并对混凝土的抗压强度、耐久性与孔结构进行了相关性分析。结果表明:改进搅拌工艺能够降低多孔类骨料混凝土的孔隙率,水灰比越低效果越好,其中珊瑚混凝土的改善效果最佳,同类混凝土,孔隙率越低,抗压强度越高;改进搅拌工艺能够有效减少混凝土的有害孔,孔径分布的改善幅度由大至小依次为珊瑚混凝土陶粒混凝土石灰石混凝土;改进搅拌工艺能够明显降低混凝土的孔体积,即降低孔的连通性,珊瑚混凝土的降幅最大,孔隙总体积与电通量存在较好的线性关系。
[Abstract]:In this paper, the effect of improved agitation process on the properties of porous aggregate concrete of two different types of coral and ceramsite is studied, and the mechanism of action is analyzed, and the reference of limestone concrete is compared. The main contents and results are as follows: the physical properties of coral, ceramsite, limestone, such as water absorption, density, void ratio, compressive strength, crushing index, needle content and so on, are tested, and the characteristics of low strength of porous aggregate concrete are analyzed. In this paper, the improved agitation process is determined by the method of sand and stone wrapping. By testing the consistency, gas content and bleeding rate of fresh concrete, the effect of the improved mixing process on the working performance of porous aggregate concrete was studied, and the mechanism of its action was analyzed. The results show that the fluidity of concrete can be improved and the amount of water reducing agent can be reduced by improving the mixing process, and the air content of concrete can be reduced by improving the mixing process, and the decrease increases with the decrease of water-cement ratio. Its effect on porous aggregate concrete is stronger than that on limestone concrete, coral concrete and ceramsite concrete are bleeding seriously because of low aggregate density, and limestone concrete has no bleeding phenomenon. Improving the mixing process can improve the bleeding rate of porous aggregate concrete, the lower the water-cement ratio, the better the effect. The influence of coarse aggregate properties on the compressive strength of concrete and the influence of the improved mixing process on the compressive strength and durability of porous aggregate concrete were studied. The results show that the order of compressive strength of three kinds of concrete from high to low is limestone concrete ceramsite concrete coral concrete, which is in accordance with the order of aggregate strength. With the decrease of water-cement ratio, the difference of strength grade between porous aggregate concrete and limestone concrete is further enlarged, and the compressive strength of porous aggregate concrete can be improved by improving the mixing process, and when the water cement ratio is low, the compressive strength of porous aggregate concrete can be improved when the ratio of water to cement is low. The increasing range of compressive strength is not obvious at the early stage, then increases rapidly with the age growth, and then decreases slightly and tends to be stable in the middle and late stage; at high water-cement ratio, the change law: the increase is obvious and more stable. When the water / cement ratio is low, the improved mixing process can obviously improve the chloride ion permeability and carbonation resistance of porous aggregate concrete, and the improvement range of chloride ion penetration resistance decreases with the increase of age. The improvement range of carbonation resistance remained stable with the change of age, and there was no obvious improvement effect at high water-cement ratio. The effect of improved mixing process on pore structure of porous aggregate concrete was studied by mercury injection test (MIP). The correlation between compressive strength, durability and pore structure of concrete was analyzed. The results show that the improved mixing process can reduce the porosity of porous aggregate concrete, and the lower the water-cement ratio, the better the effect. The better the improvement effect of coral concrete is, the lower the porosity of the same concrete is, the higher the compressive strength is. The improvement of mixing process can effectively reduce the harmful pore size of concrete, the improvement range of pore size distribution is coral concrete ceramsite concrete limestone concrete, the improved mixing process can obviously reduce the pore volume of concrete. That is to say, the decrease of coralline concrete is the biggest, and there is a good linear relationship between the total pore volume and the electric flux.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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